Posture chair



Jne 16, 1942. R. A, CRAMER rAL '2,286,468

POSTURE CHAIR Immun,

: Snoentors .APZ/Tramer Patented `l'une 16, 1942 UNITED STATES PATENT OFFICE PO STURE CHAIR Roy A. Cramer and Jesse F. Cramer, Kansas City, Mo.

Application May 1, 1939, Serial No. 270,982 Claims. (Cl. 155-164) This invention relates to posture chairs and has for its general object to produce a chair of this type in which the back member may swing rearwardly against the resistance of a spring while the seat remains non-tilting so that the abdominal muscles of the user are exercised. One of the objects of the invention is to produce a chair of this type in which the seat may be adjusted toward and from the back member, according to the preference of the occupant, to increase or decrease the length of support offered by the front edge of the seat in relation to the upper portions of the legs of the occupant of the chair, so that long and short legged persons may be comfortably accommodated, without causing a change in the spring tension of the back member and independently of the type of spring employed. In this regard the chair of the present invention is similar to that shown in our Patent No. 2,195,241, issued March 26,

In addition to the advantages of adjustment for depth of seat in accordance With the length of the legs of the occupant of the chair, another object of the invention is to provide considerable resistance to initial backward swinging or tilting of the back rest as disclosed in our application Serial No. 175,766, led November 22, 1937. In other words, our object is to provide a yielding or friction lock to hold the chair back in upright position, of such nature as to require a distinct muscular eiTort on the part of the chair occupant to shift the chair from back nontilting to back tilting position.

Another object of the invention is to produce an improved type of spring back chair, an improved sliding seat construction, and a seat support which are of strong, durable, efficient and inexpensive construction; and in order that it may be fully understood, reference is to be had to the accompanying drawing, in which:

Figure l is a side elevation of a chair embodying the invention with a cover or housing member removed to moreclearly disclose a part of the tensioning mechanism of the chair.

Figure 2 is a bottom plan view of the chair as shown in Figure 1.

Figure 3 is an enlarged section on the line III-III of Figure 1, with the supporting legs and housing member omitted.

Figure 4 is a section on the line IV-IV of Figure 3, with the housing member in operative position. V A

Figure 5 is a vertical cross section with the upper part of the seat and the parts in the background omitted.

- Figure 6 is ak reduced perspective view of the housing member.

In the said drawing, where like reference characters identify corresponding parts in all of the figures, I is a seat support which, in its preferred form, has a tubular lower portion la and welded or otherwiseY secured to its upper end is an inverted conical portion Ib having its upper end formed to generally rectangular shape. If it is desired that the chair be of the swivel type, the seat support 4I may be rotatively mounted in any suitable manner, as by being provided in the lower end of the tubular portion Ia with a plug 2 vforming a conical bearing support rotatably resting on the upper end of a post 3. The tubular portion telescopes over the post as shown, and m-ay be locked against accidental dislocation by a locking pin Ic engaging a peripheral groove 3a in the post 3. The post 3 may be vertically adjustable in a floor-engaging spider or legs 4. The exact construction of the seat support and its floor-engaging elements are immaterial to the invention, except that the seat support preferably has means to retain a seat 5 in position for `sliding adjustment backwardly and forwardly. One convenient means of providing such a construction is to form a pair of opposite side edges of the rectangular upper end of the seat support portion Ib withv a pair of opositely projecting guide flanges 6 bearing a parallel relation to each other.

y The seat 5 may have a pair of downwardly projecting parallel ribs or strips l, or equivalent arrangement, having grooves on their opposed faces in sliding interlocking engagement with the flanges 6 of the seat support (see Figure 5), so that said seat may be slid backwardly and forwardly on the seat support and be retained against upward movement should the chair be lifted by the seat, as well as to resist tilting of the seat on the seat support. In order to provide means for conveniently adjusting the position of the seat on the seat support, the seat may have a depending bar or lug member 8 having an opening in which a bolt 9 is journaled. The bolt; 9 is held against longitudinal travel through the lug 8 by means of a cotter pin or the'like IIJ abutting one side of the lug, and a hand wheel I I abutting the other side of the lug. The threaded end of the bolt 9 is threaded through a threaded opening in a lug I2 projecting from the seat support I. With this construction, it will, be evident that rotation of the bolt ber being relatively horizontal and in the shape.4

of a rectangular skeleton frame I4b, the bolt I3 engaging the long arms of the portion I4b intermediate their ends. In the.V preferred con.-

struction, as illustrated, it has been found desirable to pivot the horizontal portion I 4b intermediate its ends, so that its shorter projecting end constitutes a stop by contacting `the overlying conical portion Ib of the seat support and positively prohibits rearward swinging-or tilting of the chair back I4 beyond a fixed limit. This is aisafety measurein case the springY breaks,

as will hereinafter more particularly appear.

I 5 isa leaf spring (which is shownv as of laminated character) :secured at one end, in any suitable manner, as by a boltf I6 threaded -into a lugor enlargement I'I formedintegrally with or welded to the seatsupport I. The spring I5 in thev present construction isof U-form with its free end or leg projectingupwardly between the long side arms of the-rectangular portion I4b of the-back memberl4.- As in other chairs of this general type, the function of the spring is tothrow the back member toward the chair seat and-to resist rearward tilting of the back member by an .occupantof the-chair.

To transmit force from ythe-spring to the back memberv to throw the latter forwardly toward the seat, it will be evident that the back member must havel an abutment portion in contact with the spring, the centerv of pivotal vmovement ofthe back member on the seat support being located in relationvto the abutment and spring so that rearward pivotal movement of the back member is continuously resisted by the leaf spring. One convenient method of securing this result,` as well as of providing means whereby the tension of the spring-canbe manually adjusted, is, as: follows: A1- yoke I 6a is rockingly mounted between the side arms of the rectangular portion I4brof the-back member, and-journaled 0n a pin Hacarried-at -the upper end of the` yoke is a-roller I8 adapted-tocontact and travelon thespringwhen th'e back member is tilted. The roller I8 is held against receding underV the pressure of the spring and the spring may be adjustably tensioned-by a'longitudinally extensible member comprisingv a stem portion I9 pivotally securedto ther pin IIa, the other end of saidstemV beingfthreaded in a sleeve having a ball and socket abutment as at2I with across brace 22formingan integral part of the portion-Mb of the back member. The internally threaded sleeve ZWmaybe manually rotated in anysuitable wayto regulate theextension of the stem,I9,' as by being formed integrally with a miter gear 2Ia which is enmeshed with a second miter gear 22 keyedfon the end of a shaft 23 journaled in one side arm of theportion I4b of'the back member, and provided with ai hand wheel 24. It will be noted that adjustment of the` tensioning mechanismrshifts the axis :of the abutment rollerY I 8 to increase or decrease. the

spring tension tending to' throw the back member forwardly toward theseat.

In order that the chair back may normally remain in vertical position and require considerable force to initiate tilting movement, it has been found preferable to form the end of the spring l5 with a depression I5a in which the abutment roller I8 normally rests. This construction acts as a friction lock to hold the chair back in upright position, andin normal use, the occupant of the chair must expend appreciable conscious muscular effort to unlock the chair and cause it to swing to tilting position by overcoming the resistance of the spring suciently to move the roller I8 out of the notch I5a.

Tolend a more attractive and finished appearance to the chair, the tensioning mechanism may Ybe-housed orenclosed in a detachable housing 25.. In the present embodiment of the invention where the spring I5 is laminated, the housing,l is mounted in position by engaging its depending arm or edge 26 betweena pair of laminationsofthefspring; The -side portions 21 of the housinglare-ofsucient length to conceal the tensioning mechanismat any point in its normaltravelover the surfacefof the spring according to the'degree. to which `the'back member of the chair, is tilted.,

From the above description .itwill be. apparent thatzwe have producedaconstruction embodyingall of the features offadvantage set forth as desirable, and while we havedescribedand illustrated the preferred embodiment; it, is to be understood that we reserve thev rightV to all changes within the spirit vof theinvention and without theambit ofthe priorV art.

We claim:

1. In a chair, .aseat support, a seat carried by said seat support,Y a back member pivotally connected to the seat support, a leaf spring projecting from the seat support, a yoke rockingly mounted in the back member, a roller journaled in the yoke andfin rolling engagement with the leaf. spring, the-center of-pivotal movement of the back member being so related tothe springA thatforcefimposed by the spring on the roller tends to pivot the back member forwardlytoward the. seat when the back member is tilted'rearwardly, and'manually operable means for swingingthe vyoke to shiftA the axis of the roller in relation to the back member to increase the vtension-on said spring.-

2.In1a chair, aseat support, a seat carried by said seat support, a4r back member pivotally connected to the seat support, a leaf spring projecting from the seat support, a yoke rockinglymounted in the back member, an extensible memberAV pivoted4 to the yoke at one end and having rocking connectioniwith the back member at its other end, a roller journaled on the axis of pivotalmovement ofthe yoke and extensiblemember and in .tensioning rolling engagement with the spring, thecenter of pivotal movementV of the back `member beingA so, related to the spring ythat forceimposed by the spring tends ,to pivot ,the back member forwardly toward the seat when the back memberis tilted rearwardly, and manually operablemeans for extendingthe extensible kmember to press the roller against thespring to increase the tension thereon.

3;I In a chair, a seat-support; aseatcarried by the Aseat support, a back member pivotallyA connected to the seat support, a laminated-spring projecting from the seat support, certain laminations terminating short of adjacent laminations at one end to form a terminal socket, a tensioning device carried by the back member and contacting said spring, the center of pivotal movement of the back member being so related to the spring that force imposed by the spring tends t0 pivot the back member forwardly toward the seat, and a flanged housing for the tensioning device, said housing having a flange detachably engaged in the terminal socket formed between the laminations of the spring.

4. In a chair, a seat support, a seat carried by the seat support, a frame-like back member embracing opposite sides of the seat support and pivoted thereto, a U-shaped spring having one leg secured to the seat support and having its other leg projecting between the sides of the frame-like back member, and a tensioning device carried by the frame-like back member and abutting the spring, the pivotal point of the back member being so related to the spring that the spring tends to resist rearward tilting movement of the back member.

5. In a chair, a seat support, a back member pivotally connected to the seat support, a leaf spring projecting from the seat support and having a locking socket, a yoke rockingly mounted in the back member, a roller journaled in the yoke in rolling engagement with the leaf spring, the center of pivotal movement of the back member being so related to the spring that force imposed by the spring on the roller tends to pivot the back member forwardly until such movement is stopped by entry of the roller into the spring socket, and manually operable means for swinging the yoke to shift the axis of the roller in relation to the back member to increase the tension on said spring.

ROY A. CRAMER. JESSE F. CRAMER. 

